The ratio of the number of green stickers to red stickers is 5 : 2.
After Adam buys another 10 green stickers and 70 red stickers,
the ratio becomes of the number of green stickers to red stickers is 7 : 4.
How many stickers does Adam have now?
|
Make p the same (1) x 4 = (3) |
(1) Green |
(2) Red |
Make p the same (2) x 7 = (4) |
Before |
20 u |
5 u |
2 u |
14 u |
Change |
+ 40 |
+ 10 |
+ 70 |
+ 490 |
After |
20 u + 40 |
5 u + 10 |
2 u + 70 |
14 u + 490 |
Comparing the green stickers and the red stickers in the end |
28 p |
7 p |
4 p |
28 p |
5 u + 10 = 7 p --- (1)
2 u + 70 = 4 p --- (2)
Make p the same by using the LCM of 4 and 7.
LCM of 4 and 7 is 28.
(1)
x 4 20 u + 40 = 28 p --- (3)
(2)
x 7 14 u + 490 = 28 p --- (4)
(3) = (4)
20 u + 40 = 14 u + 490
20 u - 14 u = 490 - 40
6 u = 450
1 u = 450 ÷ 6 = 75
Number of stickers that Adam has now
= 5 u + 10 + 2 u + 70
= 5 u + 2 u + 10 + 70
= 7 u + 80
= 7 x 75 + 80
= 525 + 80
= 605
Answer(s): 605